package com.lavegue.util;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

import org.mozilla.intl.chardet.nsDetector;
import org.mozilla.intl.chardet.nsICharsetDetectionObserver;

/**
 * 借助JCharDet获取文件字符集  
 * @author icer  
 * PS:  
 * JCharDet 是mozilla自动字符集探测算法代码的java移植，其官方主页为：  
 *      http://jchardet.sourceforge.net/  
 * @author luoweibin
 * @date Oct 26, 2009
 * @description
 * 
 */
public class FileCharsetDetector {
	
	    private boolean found = false;   
	  
	    /**  
	     * 如果完全匹配某个字符集检测算法, 则该属性保存该字符集的名称. 否则(如二进制文件)其值就为默认值 null, 这时应当查询属性   
	     */  
	    private String encoding = null;   
	  
	    public static void main(String[] argv) throws Exception {   
	    	String code = new FileCharsetDetector().guestFileEncoding("C:\\Documents and Settings\\DELL\\桌面\\ttt.txt");
	    	System.out.println(code);
	    }   
	  
	    /**  
	     * 传入一个文件(File)对象，检查文件编码  
	     *   
	     * @param file  
	     *            File对象实例  
	     * @return 文件编码，若无，则返回null  
	     * @throws FileNotFoundException  
	     * @throws IOException  
	     */  
	    public String guestFileEncoding(File file) throws FileNotFoundException,   
	            IOException {   
	        return geestFileEncoding(file, new nsDetector());   
	    }   
	  
	    /**  
	     * 获取文件的编码  
	     *   
	     * @param file  
	     *            File对象实例  
	     * @param languageHint  
	     *            语言提示区域代码 eg：1 : Japanese; 2 : Chinese; 3 : Simplified Chinese;  
	     *            4 : Traditional Chinese; 5 : Korean; 6 : Dont know (default)  
	     * @return 文件编码，eg：UTF-8,GBK,GB2312形式，若无，则返回null  
	     * @throws FileNotFoundException  
	     * @throws IOException  
	     */  
	    public String guestFileEncoding(File file, int languageHint)   
	            throws FileNotFoundException, IOException {   
	        return geestFileEncoding(file, new nsDetector(languageHint));   
	    }   
	  
	    /**  
	     * 获取文件的编码  
	     *   
	     * @param path  
	     *            文件路径  
	     * @return 文件编码，eg：UTF-8,GBK,GB2312形式，若无，则返回null  
	     * @throws FileNotFoundException  
	     * @throws IOException  
	     */  
	    public String guestFileEncoding(String path) throws FileNotFoundException,   
	            IOException {   
	        return guestFileEncoding(new File(path));   
	    }   
	  
	    /**  
	     * 获取文件的编码  
	     *   
	     * @param path  
	     *            文件路径  
	     * @param languageHint  
	     *            语言提示区域代码 eg：1 : Japanese; 2 : Chinese; 3 : Simplified Chinese;  
	     *            4 : Traditional Chinese; 5 : Korean; 6 : Dont know (default)  
	     * @return  
	     * @throws FileNotFoundException  
	     * @throws IOException  
	     */  
	    public String guestFileEncoding(String path, int languageHint)   
	            throws FileNotFoundException, IOException {   
	        return guestFileEncoding(new File(path), languageHint);   
	    }   
	  
	    /**  
	     * 获取文件的编码  
	     *   
	     * @param file  
	     * @param det  
	     * @return  
	     * @throws FileNotFoundException  
	     * @throws IOException  
	     */  
	    private String geestFileEncoding(File file, nsDetector det)   
	            throws FileNotFoundException, IOException {   
	        // Set an observer...   
	        // The Notify() will be called when a matching charset is found.   
	        det.Init(new nsICharsetDetectionObserver() {   
	            public void Notify(String charset) {   
	                found = true;   
	                encoding = charset;   
	            }   
	        });   
	  
	        BufferedInputStream imp = new BufferedInputStream(new FileInputStream(   
	                file));   
	  
	        byte[] buf = new byte[1024];   
	        int len;   
	        boolean done = false;   
	        boolean isAscii = true;   
	  
	        while ((len = imp.read(buf, 0, buf.length)) != -1) {   
	            // Check if the stream is only ascii.   
	            if (isAscii)   
	                isAscii = det.isAscii(buf, len);   
	  
	            // DoIt if non-ascii and not done yet.   
	            if (!isAscii && !done)   
	                done = det.DoIt(buf, len, false);   
	        }   
	        det.DataEnd();   
	  
	        if (isAscii) {   
	            encoding = "ASCII";   
	            found = true;   
	        }   
	  
	        if (!found) {   
	            String prob[] = det.getProbableCharsets();   
	            if (prob.length > 0) {   
	                // 在没有发现情况下，则取第一个可能的编码   
	                encoding = prob[0];   
	            } else {   
	                return null;   
	            }   
	        }   
	        return encoding;   
	    }   

}
